Four Northern Virginia businessmen have been elected to fill the top posts at the Fairfax County Chamber of Commerce, an association of 1,600 member firms designed to promote business interests in the county, for the 1985-86 term.

James P. Popino, director of administration and facilities for Sperry Corp. in Reston, was named president of the business organization. Popino will succeed William Bestimt, consultant to the president of George Mason University, effective July 1.

A senior executive with the high-tech firm, Popino recently supervised construction of regional headquarters for Sperry's electronic warfare and support systems division, a 318,000-square-foot facility in Reston. At the Chamber of Commerce, Popino has been an active promoter of Washington Dulles International Airport and major road construction projects in the county.

In a recent discussion with Chamber staff, Popino said his plans for the next year will focus on "broadening horizons" for the Chamber of Commerce, according to Chamber spokeswoman Jane Rosinski. That, she said, would mean working with other business and civic groups in the area and throughout the state and "playing on Chamber membership" to promote business in the region.

In addition to that theme, the Chamber will continue to monitor transportation issues and to improve services for small-business members, Rosinski said.

Other area business leaders elected officers of the Chamber are Karl R. Nelson, secretary for Smith-Field Insurance Agency, as first vice president; Earle C. Williams, president of BDM International Inc., as secretary; and Ernest E. Bartholomew, managing partner of Arthur Young & Co.'s Reston office, as treasurer.

Nelson, who also is co-owner of Commonwealth Financial Services Network, recently served as vice president for the Chamber's economic development division. In that capacity, he helped produce the Chamber's award-winning video about Northern Virginia's transportation crisis and what legislative steps could be taken to resolve it. He has been active on a range of transportation issues and also was behind the county's Affordable Housing Coalition.

Williams, who has been a member of the Chamber of Commerce since 1976, is president and chief executive officer of BDM International Inc., a high-tech and professional services firm contracting primarily with the military. Under his leadership, annual sales at the McLean-based firm have grown from $7.7 million in 1972 to $191.4 million in 1984. Additionally, he has participated in many community, business and professional associations.

Bartholomew, an accountant, is national director of education for the accounting firm of Arthur Young & Co., in addition to being manager of its Reston office. In the past, he has been active on the Chamber's county budget and tax committee, responsible for analyzing proposed budgets for Fairfax County.

New Chamber of Commerce vice presidents will be Kaye Sloan Burke, coordinator of business/community relations at Northern Virginia Community College; Thomas Collins, public relations manager for Mobil Oil Corp.'s U.S. marketing and refining division; Jeff Davis, general manager of Surfa-Shield Corp.; Donna Foster, president of Foster Personnel Consultants; Charles Gulledge, president of S.I.3; Richard Henninger, president of Karloid Corp.; Thomson Hirst, president of the Mason Hirst Cos.; Philip Hunter, president of Hunter Associates Laboratory; Peter Stefanou, parnter in Frank, Stefanou & Co.; and Linda Wright, president of Fairfax Savings Bank.

Business leaders newly elected by the membership to serve two-year terms on the board of directors beginning July 1 include: Bartholomew, Collins and Robert Skunda, of Dewberry & Davis. William Harris, of United Virginia Bank, has been elected for a one-year term. TRADE

A new group, the Northern Virginia Minority Business and Professional Association, has been formed to promote minority businesses in that region. "I saw a need for an organization that would promote the small guy in Fairfax County," said Patricia Hairston, the association's founder. Hairston said she intends to attract members from all ethnic groups, including the large Korean, Vietnamese and Chinese populations in Northern Virginia. Hairston said she has contacted more than 50 minority business owners who have shown interest in joining the association. The first NVMBPA membership meeting will be held June 13 at GTE Telenet Corp. in Reston.

The Association of Independent Television Stations Inc. (INTV) has selected Preston R. Padden, associate general counsel of Metromedia Broadcasting of Washington, as its president. Padden replaces Herman W. Land, who is retiring after serving as INTV president for the past 13 years. INTV is based in Washington, with marketing offices in New York, Los Angeles, Chicago and Dallas.

Leon Ruben, secretary of Steven-Windsor, the men's retail outlet with 11 stores in the the Washington area, has been elected president of Big and Tall Associates. The 15-year-old association coordinates group buys for its 47 members and sponsors two trade shows a year. Ruben, first vice president of the association for the past two years, is one of its founding members.